Internal combustion engine



April 1941. K. L. HERRMANN 2.237.989

INTERNAL COMBUSTION ENGINE Original Filed Oct. 29, 1938 2 Shee ts-Sheet l INVENTOR.

#7 A #EPIMI/WV April 1941- K. L. HERRMANN 2.237.989

INTERNAL COMBUSTION ENGINE Original Filed 001:. 29, 1938 2 Sheets Sheet 2 fig. 3

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INVENTOR.

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slot being opento provide means to supply lubricant tothe Patented 8,194!

UNITED. STATES PATENT OFFICE t, m'rsnivan QOMBUSI'ION arrows KarlLHerrmsnmSouthBendJnd.

Original We; ommsaiass. Serial 8a. m sea. dad and this imilio tion my" 6.

Seriai'No. 833,519

a cum. (CL res-4s;

This invention relates to internal combustion engines and particularly internal combustion englass of the so-called barrel type, the principal object being the provision of an engine of this type having an improved connection between the connectedto the com to impart driving movement thereto, the connection between the pistons and the cam including rollers carried by the piston and having half hearings therein; the provision of an engine of the" type described in which the journals for the rollers interposed between the cam and the piston are maintained in position by engagement oithe rollers with the cam; the provision of a construction as above described in which the roller-journals are permitted a small amount of play axially of the piston whereby upon reversal in the direction of movement of the piston, movement of the Journals in their bearings will occur and serve to draw lubricant onto the active faces of the bearings; the provision oi. a construction of the type described in which the faces .of the rollers are crowned whereby to obviate the occurrence of localized areas of excessive pressure between the rollers and the cam because of misalignment of the cooperating races thereof: and the provision of a construction of the type degrally with their Journals and the pistons are formal to receive the rollers and their Journals and the rollers co-operate with the cam to maintain their journals in co-operative relation with -respecttothepistons.

. formed to provide a well of lubricant in contact with the bores of the cylinders: the provision of a constmctionias above described in which the pistons are provided with a connecting strut portion having a central slot therein closed on one side by the bore ofthe co-operating cylinders, the

reception of lubricant distributed to the of the casing whereby to and to the walls of the cylinders; the provision of a construction as above described in which lubricant is fed to the drive shaft of the engine and is discharged therefrom to the wearing surfaces of the connection between the pistons and the drive shaft: the provision of a construction as above described in which the connection between the pistons and the drive shaft includes a cam fixed to thedrive shaft and rollers interposed between the respective pistons and cam, the rollers each having a journal received in an end of the longitudinal slots in the strut'portion of the cooperating piston; and the provision of a construction of the type described in which the journals for the rollers are formed integrally therewith and the bearings for the journals are open over at least a. portion of their angular extent for direct reception of lubricant in the casing.

The above being among the objects of the present invention the same consists in certain novel features of construction and combinations of parts to be hereinafter described with referenceto the accompanying drawings, and then claimed, having the above and other objects in view.

.\ In the accompanying drawings which illustrate suitable embodiments of the present invention and in which like numerals refer to. like parts scribed in which the rollers are formed intethroughout the several dii'ierent views,

In the drawings:

- Figure lisanelevational viewpartlyinsection of abarrel type engine embodyin the present invention;

Figure 2 is an elevational view partly in section of a piston such as may be employed for the-engine shownin Figure 1;

Figure 3 is a plan view of a modified form of piston;

Figure 4 is an elevational view, partly in section, of the piston shown in Figure 3;

Figure 5 is a sectional view taken substantially on line H of Figure 4;

, Figure 6 is a sectional view taken substantially onlinet-iofliguredy' v Figure '7 is a sectional view taken on line '|--I of Figure 4; I Figure 8 is a sectional view taken substantially on line Ho! Figure 4;

Figure 9 is a view showing in detail one of the cam followers in position in the piston; and

' follower.

The present application is a division of my copending application for Letters Patent of pistons 5 United States for improvements in Internal coininumbered 237,625, such prior application being a continuation in part of my copending application for Letters Patent of the United States for im-\ provements in Internal combustion engine, filed May 14, 1937, and serially numbered 142,653. The present invention deals primarily with an internal combustion engine of the barrel type employing a cam on the drive shaft and embodying an improved form of connection between the cam and the pistons, as well as an improved means for effecting lubrication of such connection and the cylinders and pistons.

Referring now to the drawings and particularly to Fig. 1, there is disclosed an internal combustion engine, indicated generally at 5, of thebarrel type having twelve cylinders in two groups of six each. As shown in Fig; l, the engine is composed of two similar halves or blocks 89 and 29 bolted together as indicated at 8 substantially centrally of the length of the engine. The drive shaft 10 extends axially through both halves of the engine. It will be understood that the cylinders in each block are equally angularly spaced in a circle about the shaft with their axes parallel to the shaft and with corresponding cylinders in both blocks aligned with each other as, for instance, as shown and described in my copending application for Letters Patent of the United States for improvements in Internal combustion engine, filed Mayli, 1937, and serially numbered 142,653. The drive shaft has mounted on it or formed integral with it a relatively short 'diametrically enlarged portion H disposed approximately midway between the ends of the shaft, this portion being positioned axially of the engine by the thrust bearings I2 bearing against perpendicular thrust surfaces l3 formed at opposite ends of the enlarged portion II. Supported on and carried by the enlarged portion II is a T-sectioned driving cam it through which the drive shaft I9 is driven from the pistons.

The shaft i extends the entire length of the engine and is provided with journal surfaces adjacent opposite ends thereof co-operating with bearings carried by the blocks for rotatably supporting the shaft Ill. One end of the drive shaft I9 may be provided with an ignition distributor (not shown) and the opposite end may be arranged for coupling to any desired transmission mechanism or other object to be driven.

It will be noted that each cylinder block 19 and 20 is provided with a casing portion 5 and I, respectively, which casing portions are connected by the bolts 8 and the interiors of which form a cam case corresponding to the crank case of a conventional crank type of engine. Secured to the axially outer ends of the cylinder blocks l9 and 20 are cylinder heads 24. Both the cylinder blocks and .the cylinder heads are similar, and it is not believed that a detailed description thereof is necessary in describing the present invention.

On each head 24 there is secured a valve cover 25 and within each cover 25 are a plurality of valves such as indicated'at 26, co-operating with valve openings 2'! formed in the corresponding cylinder head for communication with the respective cylinders disposed about the drive shaft. Each of the blocks l9 and 20 is provided with six cylinder bores, such as indicated at 28, and each cylinder bore has associated therewith a piston 29 of a double ended piston such as is indicated generally at 30.

The double ended piston illustrated in Fig. 1 and shown more in detail in Figure 2, comprises a pair of pistons'29 and 32 connected by a connecting portion or strut 33. The connecting portion has formed therewith a pair of bearings 36 and 35 within which there are mounted roller bearings and cam followers such as 36. and 3?, the cam followers contacting with the cam is and transforming the energy of the pistons into torque for rotating the shaft 10.

As indicated in Fig. 1, the cylinder blocks 99 and 2B are each provided with a water jacket .99

surrounding the same for cooling the cylinders 28, and lubricant is supplied to the cylinders between the ends of the pistons 39 by means of a series of spiral baffles 32 and 33 mounted on the drive shaft l9 and moving lubricant from a suitable reservoir axially in opposite directions along the shaft, a portion of this lubricant passing through the thrust bearings l2 and thence into the interior of the casings 5 and 1 between opposed pistons 29 and 32.

One form or design of double ended piston is clearly shown in Fig. 2. As there shown the piston unit comprises a pair of pistons 29 and 32 connected by a connecting portion 33. The connection or center portion may be considered as a beam for transferring the load caused by the reciprocating compression and explosive forces to the skirts 92 of the piston heads. The beam in addition to supporting the follower rolls 3 and 31, transfers the loads well up into the skirts of the pistons. There the beam is secured to a rib 93 arranged transversely of the body portion of the piston and to a second rib 9i extending longitudinally of the piston but at right angles to the beam 33. This allows the expansion of the rigid rib and connects the beam through the ribs 93 and 94 to the semi-flexible skirt portion 92 of the piston head. As may be seen at 95, the piston head is slotted to allow for flexing thereof. The beam is preferably re-enforced, as at 96, to stiffen the structure through the wear pads 99 hearing on the side of the cam H. The

' center portion of the beam 33 may be of U-section, and the outboard hearing or wear pads 99 serve to prevent rotation of the pistons with respect to the cylinder bores.

Considering now the preferred form of piston shown in Figs. 3 to 9, inclusive, a piston structure 50 is shown having the opposed piston heads 52 and 53. The skirt portions 54 and 55, respectively, of thetwo pistons are slotted as indicated at 56 to provide for a semi-flexible connection between the heads and the skirt portions.

The two skirt portions 54 and 55 are connected by a central beam portion 51 which is arcuate in shape, as indicated in Fig. 5, and which is provided with a central longitudinally slotted portion 58 for a purpose to be hereinafter described. As shown clearly in Fig. 5, the beam portion 51 of the piston terminates in an angled, slightly curved surface 59 at opposite sides of the piston which form wear pads bearing on the cam follower to prevent rotation of the piston relative to the cylinder bores. In order to reduce the wear surface, the inner part of the. beam 51 may be undercut to clear the cam follower I4, and thus to provide opposed wear surfaces 59. These surfaces prevent rotation of the piston in the cylinder, while the arcuate portion of the beam 51 transmits lateral thrust directly to the cylinder wall, allowing reducing of the rib sections in the piston. v To provide rigidity of connection between the mnwumnmstnepnmsnmumau, theplston'skirtisprovidedwitbatransversereenforcedwebportioniIandwithalongitudinaily extending web portion '8 projecting at right angles to the web .2. This provides for a rigid positive connection between the beam portion and the opposed piston skirts with the slotted portions It providing the flexibility required for proper sealing of the piston heads in the cylinders. If desired to increase the strength and rigidity of the connecting beam II, the cam follower rollers may be placed below the center of the piston, thus increasing the cross-section ofthebeamandalsothelateralarcuatebearing surface between pads II.

Below the slot 68 there is provided a pair of opposed semi-cylindrical bearing surfaces 04 which are in alignment with the opposite ends of the slot It and between which and the beam portion ll of the piston there is a cut-back portion '5 adapted to receive the rollers it of the cam followers, indicated generally at 81 in Figs. 9 and 10, the rollers being confined against axial movement between the bearings N and I2. Each cam follower 61 comprises a cylindrical roller 68 having opposite trunions or journal ends '9 and II preferably formed integrally therewith as shown, the trunnions as being adapted to be received in the half bearing or end I! at the corresponding end of the slot ill and the trunnion II being adapted to be received in the semi-cylindrical bearing 64 at the lower end' of the corresponding web 62.

The bearing surfaces 64 and 12 may be formed by the metal of the piston itself, or suitable antifriction inserts may be employed in the piston to provide such surfaces if desired. It will be seen that with such a construction the rollers 66 which engage the cam follower ll are free to rotate within the cut-back portions 85 of the opposed piston skirts, while the trunnions 69 and I thereof rotate in the semi-cylindrical bearings I2 and 64 disposed at opposite sides of the cut-back portion I. The use of pairs of half bearings open on the same side allows for insertion of the cam followers into position with the piston disposed in the cylinder and eliminates the necessity of roller bearings or the like such as are required in the piston construction shown in Fig. 2. This also eliminates the necessity of lock rings and retainers for holding needle hearings in position, as required in the construction shown in Fig. 2, and greatly facilitates the assembly of the cam followers in the pistons.

The rollers 86 may have a partially spherical or crowned cam contact surfaces, if so desired and as illustrated in Fig. 10, to prevent cramping due to fiexure or manufacturing tolerances, or to compensate for any mis-alignment that might occur between the faces of the rollers and the sides of the cam ll, thereby eliminating any disadvantages that might occur frmn such cramping or mis-alignment. It will be understood that the crown of the roller 66 as shown in Fig. is exaggerated for the purpose of explanation.

It will be apparent from an inspection of Fig. 1 that the lubricant, directed by the spiral bailie 42 or otherwise along the shaft l0 and through the thrust bearings l2 and into casing portions 6 and l where it will be discharged under centrifugal force intermediate the pistons 29 and 32, or 52 and 53, will be thrown backwardly and forwardly upon reciprocation of the double-ended pistons, and will be splashed directly against the surfaces of the trunnions 69 and Ill exposed in the half bearings 64 and I! as well as on the cam suran explosion at the corresponding end of the associated piston, it is obvious that this film of lubricantwillbepassedontothesurfsoesofthe bearings 84 and II to insure adequatelubrication thereof without the necessity of using anti-friction bearings to journal the trunnions. Also, it will be noted that the cut-back portions II in the piston skirts are slightly greater than the diameters of the rollers 60, thus providing sumcient clearance to insure free movement of these rollers and also accommodating wear of the hearing surfaces 64 and 12 before the roller I will engage the surface of the cut-back portion II.

It has been found preferable to so space the opposite pairs of bearing surfaces 4 and I! from each other as to provide a slightly greater distance between pairs of opposed rollers it. when fully seated in their corresponding bearings 14 and I2, than the effective width of the tracks [4 received between them so that, upon reversal of direction of reciprocation of a piston, the trunnions 69 and ill of the roller on that end of the piston opposite to which an explosion of combustible mixture is exerting its force, may withdraw slightly from the bottom of its corresponding bearing surfaces 64 and 12. Accord-- ingly, the lubricant within the casings -l, either in liquid or vapor form, which comes in contact with the surfaces of the trunnions i! and II exposed on the open sides of bearings 64 and I2 and which overlies the outer and end faces of these hearings, is drawn to the back faces of the bearings by the suction created by this movement of the trunnions out of their bearings upon reversal of direction of reciprocation of the piston. This pumping effect on the lubricant by the movement of the trunnions G9 and 10 into and out of their respective bearings serves to continually feed a supply of oil to the back portions of the bearings and insures ample lubrication of the bearings at all times.

Furthermore, the slots 58 in the connecting portions 51 of the piston serve as wells to receive and retain a certain amount of lubricant during operation of the engine. The outer faces of these slots radially of the axis of the engine are,

of course, closed by the cooperating walls of the cylinders, their radially inner faces are open, and the oil thrown centrifugally off of the cam l4 and other rotating parts within the casing 81 tends to collect in the slots 58. The lubricant in such slots being in direct contact with the bore of the cooperating cylinders insures an ample supply of lubricant both to the bores of the cylinders and to the wearing surfaces of the pistons.

I have found in experimentation that sumcient lubrication is provided on the journal surfaces. 64 and 12 to prevent any appreciable wear thereof during a period substantially equivalent to the life of such an engine. If desired, hearing metal inserts, such as bronze or babbitt, might be provided for these surfaces or the metal might be hardened at these points if so desired.

It is, therefore, believed apparent that I have provided a novel type of double-ended piston which is very simple in design and assembly, which requires no complicated anti-friction bearing assembly, and which can be readily inspected and maintained in properlylubricated faces of the cam ll. Inasmuch as the rollers it condition at all times.

n is to-be understood that the above described embodiments of the invention are for the pur- I poses of illustration only, and various changes may be made therein without departing from the scope and spirit of the invention.

What is claimed is: a

i. In an engine structure, in combination, a shaft, a pair of opposed cylinders arranged approximately parallel to said shaft, a double end- I pair of said bearing surfaces, the construction and arrangement of said cam, rollers, trunnions and bearing surfaces being such that said trunnions are permitted a small degree of movement axially of said piston during reversal of forces thereon whereby to effect a pumping action on lubricant supplied thereto to maintain said bearing surfaces in constantly bathed condition.

2. In an engine structure, in combination, a

' housing including a pair of opposed cylinders arranged in axially spaced relation and in approximate alignment with each other, a shaft rotatably mounted in said housing in approximate alignment with the axes of said cylinders, means for distributing lubricant within said housing, a double-ended piston one end of which is received ineach of said cylinders, said piston having two pairs of bearing surfaces, said pairs of bearing surfaces being spaced from each other axially of said piston and the bearing surfaces of each pair being spaced from each other diametrically of said piston, a cam secured to said shaft and projecting between the said pairs of surfaces, a roller on each side of said cam in contact therewith and interposed between said diametrically spaced bearing surfaces of the corresponding pair of bearing surfaces, each of said rollers having trunnions projecting axially from opposite ends thereof and received by the corresponding pair of bearing surfaces, said bearing surfaces being circumferentially broken whereby to expose a material area of the surfaces of said trunnions adapted for engagement therewith to direct contact with said lubricant distributed in said housing.

3. An internal combustion engine comprising, in combination, a casing providing a chamber and a cylindrical bore therein, the walls of said bore intermediate the ends thereof being cut away on one side thereof so as to provide open communication between the chamber and said bore and to form said bore into opposed and axially spaced cylinders, a double ended piston in said bore including piston-like end portions and an interconnecting strut substantially contacting the wall of said bore opposite the cut away portion thereof, a rotatable shaft in said housing arranged with its axis in approximately parallel relation with respect to the axis of said bore, a cam on said shaft, and a pair of rollers carried by said piston and engaging opposite sides of said cam, said strut having a longitudinally extending slot therethrough providing a lubricant reservoir in said piston, the bottom of said reservoir being closed by the wall of said bore whereby the wall of said bore is open to constant and direct lubrication.

KARL L. HERRMANN. 

